OnePlus
Audio Balance: Left/Right Adjustment auf OnePlus
If one ear picks up sound louder than the other, an uneven audio balance is usually the cause, not a hardware fault. OnePlus phones running OxygenOS include a dedicated audio balance slider in the accessibility settings that shifts volume continuously between the left and right channel.
Where to find the audio balance setting
Open the Settings app, then tap System, followed by Accessibility. Inside this menu you find the audio balance slider. Swipe it left or right to shift more volume toward one ear.
The adjustment applies system-wide, so it affects calls, media playback, and notification sounds through both wired and Bluetooth audio devices.
Move the slider in small steps and test with familiar audio, since large jumps make the change hard to judge accurately.
If the imbalance only shows up with one specific headset, check that device's own volume levels first. Changing the system-wide balance here will also affect every other audio source connected to the phone.
Move the slider back to the center position whenever you want default balanced output again.